Various imaging systems have been developed in the art to produce stereoscopic or 3D images. These systems generally consist of a method for creating two images as seen from a different perspective and means for displaying the images so that one eye sees one perspective of the image and the other eye sees a different perspective of the image to produce a 3D image.
One method is based on the use of separate spaced apart optical means to produce two perspectives of the same image. The images are displayed side by side, such as on film or on a cathode ray tube (CRT). Means are provided so that the left eye sees only one image and the right eye sees only the other image so that the image as processed by the brain appears as a stereoscopic image.
One example of such a system is found in U.S. Pat. No. 3,784,738 issued Jan. 8, 1974 to Howard Natter for producing stereoscopic video. Natter employs an image displacer which creates two images as viewed from different perspectives. As an alternative Natter can employ two spaced apart video cameras to create two images of the scene. These images are broadcast to receiving station which transmits the images to a CRT where they are displayed side by side. If two cameras are used the images are displayed on separate CRT. The CRT is mounted in headgear having spaced apart viewing windows so that only one eye can view one image. This system relies heavily on the fact that the two images must be shot and kept perfectly synchronized, or the image will deteriorate.
Similarly, U.S. Pat. No. 4,303,316 issued Dec. 1, 1981 to Robert McElveen discloses a two camera system for recording left and right perspectives of a scene. The images are then combined on a film strip in a sequence of left and right views with non-moving parts of the scene super imposed. In this manner stereoscopic projections on a two dimensional surface can be seen with unaided eyes. As an alternative a single camera having a shutter that alternately record left and right perspectives of a scene can be used.
Other systems employing several cameras or optical means for creating left and right image perspectives which are the displayed alternatively to create a stereoscopic effect are disclosed in U.S. Pat. No. 3,251,933 issued May 17, 1966 to H. E. Beste; U.S. Pat. No. 4,523,226 issued Jun. 11, 1985 to Lipton et al.; U.S. Pat. No. 5,142,642 issued Aug. 25, 1992 to H. Sudo; and U.S. Pat. No. 4,751,570 issued Jun. 14, 1988.
Another method involves moving the camera and image with respect to one another to produce stereoscopically related images. These images can be displayed sequentially to provide a stereoscopic image without the aid of a viewing device. Alternatively, a viewing device or apparatus can be used which in effect causes the left eye to see a left perspective and the right eye to see a right perspective of the image. These systems allow for the use of a single sensor.
In U.S. Pat. No. 4,807,024 issued Feb. 21, 1989 to McLaurin et al. a single camera is disposed on a moving platform and the stereoscopically related images are presented alternately so that the resulting image is perceived as having depth. No special viewing device or glasses is required.
U.S. Pat. No. 4,754,327 issued Jun. 28, 1988 to Thomas Lippert also employs a single sensor on a horizontally moving platform for producing left and right perspectives of an image as the sensor moves. The images may be displayed as separate frames for the left and right eye to provide depth to the image. The images may be separated by differences in polarity of light or sequentially to the left and right eye.
U.S. Pat. No. 4,943,852 issued Jul. 24, 1990 to Fermano et al. discloses a converter for attachment to a conventional video camera which has shutter means for alternately presenting to the video camera left and right side perspectives of the image being recorded. A viewer included voltage activated light valves to alternately present to the view the left and right side perspectives of the image to create a 3D effect.
U.S. Pat. No. 4,723,159 issued Feb. 2, 1988 to Donald Imsand combines a reference camera and a moving dynamic camera to produce stereoscopic images. As an alternative to moving the dynamic camera, Ismand can use rotating mirrors to create the effect of moving the dynamic camera. Ismand teaches the repositioning of objects close to the dynamic camera, which appear to move due to the movement of the camera or mirrors, to positions as recorded by the reference camera. This technique is referred to as "global convergence".
While the systems described in the foregoing patents may effectively provide stereoscopic images, it will be apparent that they require additional equipment such as extra cameras and processing equipment or awkward moving platforms.
U.S. Pat. No. 5,151,821 issued Sep. 29, 1992 to Mortimer Marks uses the horizontal movement of a pair of mirrors arranged at an angle to deflect the image into the lens of a single camera or sensor to create left and right images of different perspectives as the mirrors travel. These images may then be viewed as a stereoscopic or 3D image through photopic scotopic filters. The images appear as conventional two dimensional images when viewed without the filters. Although cutting down on the extra equipment required with some 3D systems, the Marks system produces dead spots, that is frames which are not in 3D at the point where the travel of the mirrors is reversed. These dead spots are noticeable when viewing a motion picture or video shot using the Marks system. In addition the equipment used to mount the moving mirrors is bulky and awkward to operate, especially at sporting events and other live TV presentations. It also has difficulty in focusing in the telephoto range.
To simplify the production of 3D images, devices have been proposed for attachment to the lens of a conventional camera or to replace the conventional lens of a camera. Thus, U.S. Pat. No. 4,295,153 issued Oct. 13, 1981 to Stephen Gibson describes a device for producing stereoscopic images which is designed to attach to a conventional camera body, motion, video or still, in place of the normal lens. The device includes first and second spaced apart lenses for obtaining left and perspectives of the image. Light rays from the first and second lenses travel essentially equal distance to the recording device to produce superimposed stereoscopic images of equal size. The image is viewed in 3D through glasses which permit the left perspective to be viewed through the left eye and the right perspective through the right eye. U.S. Pat. No. 4,568,970 issued Feb. 4, 1986 to Walter Rockstead is a device which is adapted to be placed in front of the lens of a video camera to produce side-by-side left and right rectangular images. The same device can be used by the viewer to view the side-by-side images in which case the device is adjusted to deliver the left and right images to the viewers left and right eyes respectively to produce a stereoscopic effect. These systems require special viewing devices in order to view the side-by-side images or adjustment must be made to the lens device, in the case Gibson, in order to view the conventional 2D image. Once this adjustment is made the scene is recorded in conventional 2D.
Accordingly it would be desirable to have a device which is readily fitted on the body of a conventional motion picture camera or video camera which will allow the recording of a scene stereoscopically but which, at the same time, also improves the quality of the projected scene when viewed by the unaided eye.